The utility model relates to a unit reserve granary, which comprises at least one layer of granary room, wherein each layer of granary room comprises a plurality of storage units with independent and controllable storage conditions, the grain storage capacity range of each storage unit is 5 to 1000t, each layer of granary room comprises an operation region for carrying out independent granary inlet and outlet operation on one or a plurality of storage units, each storage unit with the independent and controllable storage condition comprises a temperature monitoring system, a humidity monitoring system, a gas ingredient monitoring system, a ventilation monitoring system and/or a fumigating system, each storage unit has heat insulation and thermal isolation and/or air tight functions, the operation region can be arranged at both sides or one side or the middle of the granary room, and fixed and/or movable conveying equipment is arranged in the operation region. The unit reserve granary has the advantages that the storage period of the grain can be prolonged, the energy consumption is reduced, the usage number of chemical fumigants can be reduced, the environment pollution is reduced, each storage unit and the operation region are mutually separated through the arrangement of the storage unit, the mutual influence is avoided, the scientific management is convenient to carry out, and the operation cost is saved.